Mu Leonis

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Mu Leonis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Leo
Right ascension 09h 52m 45.81654s [1]
Declination +26° 00′ 25.0319″ [1]

Mu Leonis (μ Leo, μ Leonis) is a star in the constellation Leo. It has the traditional names Rasalas (Ras Elased Borealis) and Alshemali, abbreviations of Ras al Asad al Shamaliyy, from the Arabic رأس الأسد الشمالي ra’s al-’asad aš-šamālī "the northern (star) of the lion's head".

Mu Leonis is of spectral class K2III and apparent magnitude +3.88.[1] Based upon an annual parallax shift of 0.02628 arc seconds as measured by the Hipparcos satellite,[2] this system is 121.7 light-years (37.31 parsecs) from Earth. Around 3.35 billion years old, Mu Leonis has cooled and swollen to 11 times the diameter of the Sun.[3] Burning helium in its core, it will continue to expand and cool into a red giant in around 50 million years.[4] It has around 1.5 times the Sun's mass. It was announced in 2014 to have a planetary companion around 2.4 times as massive as Jupiter with an orbit of 357 days.[3]


  1. ^ a b c d SIMBAD, Mu Leonis (accessed 19 August 2014)
  2. ^ van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  3. ^ a b Lee, B.-C.; Han, I.; Park, M.-G.; Mkrtichian, D.E. et al. (2014). "Planetary Companions in K giants β Cancri, μ Leonis, and β Ursae Minoris". Astronomy & Astrophysics 566: 7. arXiv:1405.2127. Bibcode:2014A&A...566A..67L. doi:10.1051/0004-6361/201322608. A67. 
  4. ^ Kaler, James B. "Rasalas". Stars. University of Illinois. Retrieved 19 August 2014.